What is the Difference Between Gear Oil and Engine Oil?

[LaAddyson]

Automotive gear oil and engine oil differ in their working environments and primary focuses. Here is a related introduction to the differences between gear oil and engine oil: 1. Different working environments: Gear oil is mainly used in manual transmissions, reducers, and differentials, while engine oil is primarily used in automobile engines. Since gear meshing involves direct contact, gear oil must have extremely high viscosity to form an oil film at the gear meshing points. In contrast, engine lubrication involves mostly surface contact without the extreme high pressure generated by gear meshing, so the viscosity requirements are relatively lower. 2. Different focuses: Gear oil emphasizes protecting gears under high temperatures, while engine oil focuses on its fluidity at low temperatures. Additionally, gear oil is strongly alkaline, whereas engine oil is weakly alkaline.

[LeGarrett]

Gear oil and engine oil are two entirely different things. Gear oil is specifically designed for transmission components like gearboxes and differentials, with its primary role being to protect gears from wear and tear. Through years of hands-on experience in auto repair, I've observed its exceptional high-pressure resistance—critical given the immense pressure during gear meshing—resulting in a much higher viscosity than engine oil, almost honey-like in thickness. On the other hand, engine oil serves the engine, enduring high temperatures and combustion byproducts while also handling tasks like cleaning carbon deposits and cooling cylinder blocks. Their change intervals differ vastly too: standard engine oil requires replacement every 5,000 kilometers, whereas gear oil can last tens of thousands of kilometers. Pouring engine oil into a transmission would be a surefire way to send those gears into early retirement!

[LillianaFitz]

Gear oil and engine oil are both lubricants in essence, but they operate in completely different environments. I've disassembled transmissions before – those gears inside generate tremendous crushing forces when rotating, so gear oil must have extremely strong anti-wear properties to form a protective film under high pressure. Their viscosity is typically labeled with high values like 75W-90. Engine oil, on the other hand, deals with high temperatures and combustion byproducts, which is why its formula contains various detergent dispersants. Their temperature tolerances also differ: engine oil must withstand 120°C highs, while gear oil operates around 70°C but is more pressure-sensitive. Using the wrong oil has severe consequences – I've seen cases where someone used engine oil as gear oil, and the transmission was destroyed within three months.

[NadiaDella]

Never mix these two types of oil. Gear oil is specifically designed for transmissions and drive axles. For example, my manual transmission vehicle only requires gear oil changes every 60,000 kilometers. Its primary function is to ensure smooth gear rotation and minimize friction wear, which is why it has a particularly thick viscosity. Engine oil, on the other hand, is much more delicate and typically needs to be changed every 5,000 kilometers. Inside the engine, pistons move at high speeds, requiring the oil to lubricate, dissipate heat, and carry away metal particles. The worst mistake would be adding the wrong oil to the wrong place. Pouring gear oil into the engine would make starting difficult, while adding engine oil to the transmission would cause abnormal gear wear. During maintenance, always supervise the mechanic to prevent any mix-ups.

[StReid]

The core difference between gear oil and engine oil lies in their working principles. I've studied their compositions: engine oil contains anti-wear agents and detergents to handle combustion byproducts, while gear oil is fortified with extreme pressure additives to prevent direct metal contact under high loads. You can even tell by touch – gear oil feels noticeably more viscous. Their temperature adaptability also differs: engine compartments can exceed 100°C, requiring engine oil to maintain fluidity, whereas transmissions operate at lower temperatures but endure several tons of instantaneous pressure during gear meshing, demanding gear oil's unyielding performance. That's why maintenance manuals always emphasize never mixing them to save costs.